Crane weight and radius indicator



April 8, 1947. w. R. MARTIN ET AL CRANE WEIGHT AND RADIUS INDICATOR Filed Oct. 26, 1945 3 Sheets-Sheet 1 web April 8, 1947. w. R. MARTIN ET AL 2,413,593

CRANE WEIGHT AND RADIUS INDICATOR Filed Oc'l:u 26, 1943 5 Sheets-Sheet 2 APl'il 8, 1947 w. R. MARTIN ET AL 2,418,593

CRANE WEIGHT AND RADIUS INDICATOR Filed Oct. 26, 1943 5 Sheets-Sheet 5 Patented Apr. 8, 1947 UNITED STATES PATENT OFFICE CRANE WEIGHT-AND RADIUS INDICATOR Application October 26, 1943, Serial No. 507,732

6 Claims.

This invention relates to an indicating structure, and particularly pertains to a crane weight and radius indicator, and is a continuation in part ofv our application for United States Letters Patent Serial No. 445,312 filed June l, i942.

In the operation of hoisting apparatus, and particularly cranes of various types, a platform suitably supports a control cab and an adjustable boom. The boom is fitted at its outer end with a main block carrying tackle controlled from the cab. A vertically swinging boom has attached to it boom rigging,.whereby the Vertical inclination of the boom may be adjusted. In other types of cranes the effective length of the boom may be changed by other than vertical swinging action. It is well known that the maximum weight supporting strength of a boom depends upon the overhanging length of the boom, and in vertically swinging cranes varies with the angle of inclination of the boom to the horizontal. This length is designated by a factor known as the radius of the boom. swingingk boom the radius is measured along a horizontal plane intersecting the heel pin of the boom and extending from the vertical axis oi the -craneto a line perpendicular to the horizontal plane and intersecting the point of support of the main hoisting block upon the free end of the boom, It will thus be evident that the aforementioned horizontal plane measured from the heel pin to said perpendicular line will represent the base of a triangle, and that the length of the boom will represent the hypotenuse of the triangle, with the remaining side of the triangle represented by the perpendicular line of altitude. The angle between the base and the hypotenuse will vary as the boom swings vertically toward and away from the plane of the base. At the same time the base line will vary in length representing diiierent lengths of radii.r Upon the different lengths of radii and the corresponding angle between the base and hypotenuse of the triangle the maximum weight carrying capacity of the boom in any set position is determined. Heretofo-refit has been necessary for an experiencecl` operator to approximate the set angle of the boom and the radius. In instances where the crane operators estimate was inaccurate disastrous results occurred due to the fact that when an attempt was made to lift a greater load at the free end ci` the boom than the vertical angle of the radius and boom would justify parts were strained and broken. It is also obvious that in other types of cranes, such for example as On cranes having a vertically traveling, hammer head, stifileg, and jib cranes, l

whereby the radius of the boom is directly in-y dicated, as well asthe maximum weight to be lifted for a given radius, and indicating means then function to indicate the amount of weight or lifting force which is being imposed upon the boom, whereby a direct reading can be obtained to indicate the amount of load being lifted and to indicate when the magnitude of the load exceeds the maximumy for the set radius of the boom.

The invention contemplates the provision of indicating means associated with the boom ofr a crane, whereby a dial will be moved to indicate the' maximum load to be lifted by the boom at a set radius, said structure also including weight responsive means acting to move an indicating hand with relation to a dial to designate the amount of strain being placed on the hoisting cables or the amount of load being lifted.

The invention is illustrated as showing a boom type crane, by way of example, in the accompanying drawings, in which:

Figure 1 is a View in perspective showing a boo-m crane with the indicating mechanism applied thereto.

Fig. 2 is a view in diagram showing the position` ofthe "various elements of the invention and they manner in which the boom radius is calculated.

Fig. 3 is a view showing the dial of the indicating element when set for a particular radius.

Fig. 4 is a View showing the dial. of the ndicating device with the indicating yhand moved in conjunction with the dial face.

Fig. 5 is a view showing the indicator with the cover plate removed to disclose the operating mechanism and the Bourdon tubes.

Fig. 6 is an enlarged View in section and elevationY on the `line ioi Fig. 5 showing the dial and indicator 'hand 'operating mechanism with parts broken away for the sake of clearness.

Fig. 7 is an enlarged fragmentary view showing the manner in which the tackle and main hoisting block are mounted at the end of the boom. n

Fig 8 is an enlarged view in section showing the angle indicator reservoir.

Referring more particularly to the. drawings,

l0 indicates a platform or tower upon-which a 3 a power unit I3, Extending upwardly above the structure and rotatable with the turntable is a mast I4. Mounted upon the turntable is a boom I5. The boom I5 is suitably pivoted for vertical movement upon a heel pin I5. A boom rigging is provided including cables Il, one of which is attached to the free end of the boom, as indicated at I8. A block i9 may form a part of the boom rigging so that a cable 29 may pass around a sheave 2l carried at the upper end of the mast and may be led downwardly, as indicated at 22, to the power unit, which includes a winding drum not shown in the drawings.

Mounted upon the boom I5 and adjacent to its free end is a sheave 23 over which a hoisting cable 24 is led to a suitable winding drum forming a part of the power unit generally indicated at I3. The hoisting cable '4 is led around a pair of sheave blocks 25 and 25 which are suspended from the ree end of the boom. The sheave block 25, which is part of the main block, carries a hook 21 or a sling by which an object to be lifted may be engaged. Interposed between the main sheave block 28 and the secondary sheave block 25 is a fluid responsive unit 28. This unit is of the general type covered by Patent No. 1,771,340 issued to Walter R. Martin, one of the joint applicants herein, on July 22, 1930. This generally includes a hollow receptacle 29 here shown as secured to the sheave block 25 by a cable 38. A diaphragm BI closes the open side of this receptacle and is flexible, A pressure plate 32 bears against the diaphragm and is tted with a post 33 which engages a cable length 24', Fluid is disposed within the cavity formed by the housing of the receptacle 2S and the diaphragm 3l so that as tension is applied to the hoisting cable 24 the diaphragm will flex in proportion to the force exerted. A tubular conduit 34 connects with the chamber in the structure and leads to an indicating device generally indicated at 35 in Fig, 5 of the drawings. rihus, as tension increases upon the cable 24 in an effort to lift the load which may be imposed upon the hook 21 the magnitude of the force imposed will be transmitted to the indicator 35 and there visually indicated.

The fluid responsive structure 28 is shown located between the sheaves 25 and 26 and as illustrated in Fig'. 7 of the drawings it is placed upon the dead end 24 of the hoisting cable. The post 33 will engage the cable at a point intermediate hooks 35 and 31, so that as the force tends to straighten the dead-end length of cable 24 force will be imparted to the diaphragm 3I to expel the incompressible uid within the structure and to force it through the conduit 34 to the indicator 35,

Referring more particularly to Figs, 5 and 6 of the drawings, it will be seen that the indicator 35 is provided with a circular housing 38 Within which concentric Bourdon tubes 39 and 40 are positioned. The tube 39 is outermost and is spaced from the tube 49. These tubes are connected with a manifold block 4I through which are passageways for uid entering the tubes. An extension tube 4 2 is connected with the manifold block 4I and communicates with the Bourdon tube 38. For convenience, the Bourdon tube 39 will be designated as the boom tube, and the Bourdon tube 40 will be designated as the weight tube. The extension tube 42 leads to a connection 42 carried on the housing 38 and to which a conduit is attached for a purpose to be hereinafter described. An extension tube 43 connects with the manifold block 4I and establishes com munication with the weight tube 40. A connecting structure 44 is carried by the case 38 and provides an attachment for the extension tube 43 The conduit 34 is attached to the connection 44 and leads to the weight indicator structure generally indicated at 28 in the drawings.

The boom Bourdon tube 39 is tted at its free end with an adjusting link 46 which is attached to a gear segment 4l through an adjustable extension 4l'. The gear segment 4l is mounted on a pivot pin 48 in a bearing irame structure shown in detail in Fig. 5 of the drawings. The gear segment 47 is in mesh with a pinion 48 carried upon a sleeve 43 rotatably supported in the bearing structure. The free end of the weight Bourdon tube 48 is provided with an adjustable and resilient link structure 5] which is attached to a gear segment 5I through an adjustable extension 5I. The adjustable link 58 is formed With a resilient U-shaped portion 52, the effective length of which may be changed by a sliding block 53, for a purpose to be hereinafter set forth. The gearsegrnent 5I is mounted upon a pivot pin 54 which is carried by the bearing structure, The teeth of the gear segment 5I are in mesh with a pinion 55 fixed upon a pin r55 which extends upwardly through the bearing structure and the sleeve 45. rEhe bearing structure is formed with a post 5'! which carries a pair of coil springs 58 which are secured to the sleeve 49 and act in opposition to the distension of the boom tube 39. rI'his post also carries a coil spring 59 secured to the pin 5S. This operates in opposition to the action of the weight tube 4U to restore the shaft 55 to its original position. It is to be understood that stops are provided to limit the swinging movement of the gears 4'I and 5I, although they are not shown in the drawings. In order to protect the springs 58 so that they will not become entangled with the gears, shield discs SQ are mounted upon the sleeve 49. The sleeve 49 carries a central iitting 6I upon which a boom angle indicating disc 62 is secured, This moves with relation to a fixed dial ring 63, Fixed upon the upper end of the shaft VSI5 is a weight indicating hand 64. This moves over the face of the boom angle disc 62 and also with relation to the graduations cn the fixed indicating ring 63.

The indicator disc 62 is moved automatically with reference to the vertical angular relation of the boom I5. This is brought about by a reservoir 55, which is in the shape of a cylindrical container or bucket having a cover 66 formed with a central opening 5?. The opening S1 cornmunicates with the atmosphere, and within the bucket a liquid is placed, preferably of a nonevaporating character. A bail 58 is connected to the reservoir and is pivotally mounted upon a member 68 carried at the free end of the boom. Thus, at all times the reservoir is swinging free to assume a vertically aligned position irrespective or" the verticaliy inclined position of the boom I5, Connected with the lower end of the reservoir is the tubular conduit 45, which leads to the connection 42 through which communication is established with the Bourdon tube 39, It will be seen that as the angular position of the boom I5 changes the reservoir will be raised or lowered, as the case may be, and the hydrostatic head of the liquid within the reservoir and the conduit i5 will be changed directly in proportion to the angle of the boom. Thus, varying hydrostatic pressure will be created through the Bourdon tube 39 to rotate the disc 62.

When the dise di! is in position with the boom extending horizontally, a pointer 10 on the disc 62 will be in alignment with a graduation 1| on the fixed dial 63. The dial 63 is formed with two sets of graduations disposed concentrically. The inner graduation extends along a band 12 and indicates the radius in feet of the boom I5. It has previously been explained that the radius in feet represents the distance from the center oi the crane turntable to the point of support of the main hoisting block 3G as measured in a horizontal plane. An outer band of graduations 13 is mounted upon the iixed dial 63 and represents the capacity of the boom in tons for a particular radius. The movable disc 52 is formed with graduations 14 over which the hand 5t swings. These graduations represent the amount of lifting force being applied to the boom cable, and it will be evident that when the pointer 1i) on the disc G2 moves to register with a graduation along the band 13 the maximum safe load capacity of the boom at a set radius will be indicated, and that thereafter the movement of the hand 64 over the disc 52 will apprise the operator of the actual load being lifted.

.From the foregoing description it will be recognized that while the boom is being adjusted to a desired angle that the boom angle disc 62 and the indicating hand must move in unison with the point oi the indicating hand in register with the pointer 'Hi on ie disc E2. This feature or the invention is basically important, since the pointer must designate the angular position of the boom, with reference to the graduations 12 on the indicating ring @Zi and with reference to the graduations 13 on the indicating ring B3, which reading will indicate the safe load to be raised at a desired radius. In order to bring this action. about the conduit which leads from the weight indicator 28 to the indicator structure 3-5 is lled with liquid and will produce a hydrostatic head in the conduit LPA depending upon the angular position of the boom. This variation in hydrostatic head will act through the weight Bourdon tube do to move the lever extension 5I and the gear segment 5l. It is to be understood also that the conduit l5 is filled with liquid. and that a hydrostatic head will thus be established in the conduits (ill and L55. This hydrostatic head will change in value in both conduits simultaneously as the boom is raised and lowered, It is necessary to insure that this simultaneous change will act through the Bourdon tubes 39 and :lil to' move the boom angle disc (i2 and the indicating hand @il simultaneously and in unison. In order to do this the connecting link is secured to the free end of the Bourdon tube 39 and is attached to the extension 41 of the gear segment d'5. The connecting link 5i! is attached to the free end of the tube 40 and is also attached to the extension 5i of the gear segment 5l. These links are so adjusted as to insure that the sleeve 49 and the shaft 5S shall rotate in unison when the boom angle changes. To obtain acourate adjustment the adjusting block 53 may be moved back and forth on the U-shaped spring oithe link structure 50. This will determine the length of the link structure to a nicety..

in operation of the present invention the structure is assembled as here shown, and the conduits 3d and t5 are led from approximately the same position at the end of the boom to the indicator device 35 to which they are attached at h1 and 42, respectively. At this time the boom isfstanding in its extreme horizontal position and the hook 21 is supported from the cable 2E without any weight on it. The zero (0) point of scale 14 and the pointer 1G on dial 62 and the pointer S4 then coincide with the graduation 1| on fixed indicating ring S3. The boom is then manipulated to obtain a desired radius. As it does this its outer end will be elevated and will increase the hydrostatic head of liquid in conduits 34 and i5 simultaneously. This results in simultaneous movement of the boom angle disc 2 and the indicating hand 64 with relation to the iixed indicatingr ring The boom angle disc E2 will move with relation to the fixed indicator ring @3 so that the zero point on the line of calibrations 'id and the pointers Gil and 1Q will move to register with the calibrations on the iixed indicator ring. This will indicate the radius produced by the angularity or the boom andalso the safe load to be lifted by the boom when disposed at that particular radius. For example, rin Fig. 3 of the drawings the pointer 13 on the disc (i2 is in register with approximately the point 12.5 on the calibrations 13 of the indicator ring and the point '78 of the calibrations 12, Simultaneously with this registration the indicator hand @il moves to the same point. The registration thus indicates that the boom radius is '13 reet and that a sare load is 12.5 tons. In view of the fact that the boom angle will not change while lifting the load the boom angle disc will now remain stationary, and as the load is imposed on the hook 21 the indicating hand 64 will swing over the face ofthe disc 62, and as it swings over the graduations 'ifi the weight imposed upon the hook will be indicated by the hand 5a as shown in Fig. 4. When the hand 64 reaches the calibration 12.5 on the disc 62 the operator will then be apprised of the fact that he has imposed all of the load upon the hook which would be a safe load, The only way that he could safely lift a heavier load would be to shorten the boom radius, and when that is done the disc will rotate to bring the pointer 10 into register with other calibrations on the xed indieating ring agreeing with the angular disposition of the boom. At this same time the change in hydrostatic head in the conduit 34 would move the indicating hand eli in unison therewith.

Figure 2 is a view in diagram illustrating the manner in which angles of force change when.

theA boom is disposed at different angles to the horizontal. The dimension D is the actual radius of the boom as measured from the vertical axis of the boom to a line perpendicular to the end .w ofthe boom. The dimension D is the important distance to consider, since that will determine the overhang of the boom load from the center of the crane. The dimension A represents the actual length of the boom from the pin I6. The dimension E represents the distance between the central axis of the boom to the vertical axis intersecting the pin I6. The dimension C represents the height oi" the end of the boom with relation to the cab oor, and in this case would be the altitude of a triangle forming a part of the calculations automatically made by the present instrument. The factors B and F are angles of inclination of the boom relative to the horizontal plane intersecting the axis of the boom pivot l, and the dimension G represents the height of the gauge above the horizontal plane of the aXis of the pivot l5. All of these dimensions and angles normally ligure in a calculation to determine the safe load to be lifted by the boom at any radius length D. The

present device makes all of these calculations automatically and instantly and gives a direct reading on the dial of the instrument, as shown in Fig. 3.

It will thus be seen that the apparatus here provided and associated with a crane boom automatically acts to give the operator a direct reading of the boom radius at all times and a direct reading of the safe load which could be carried at that radius, and that furthermore, the amount of weight imposed upon the boom can be read at all times, all of said readings being presented in the face of one instrument, where the readings may be simultaneously observed.

While we have shown the preferred form of our invention as now known to us, it will be understood that various changes may be made in combination, construction and arrangement of parts by those skilled in the art, without departing from the spirit of the invention as claimed.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. In combination with a crane including a boom having a hoisting block at the free end thereof and means by which the radius of the boom may be set adjustably, load responsive means associated with the hoisting lock, an indicating structure including a xed dial having thereon graduations indicating boom radii, a movable dial carrying graduations indicating the load imposed upon the boom and having a pointer moving with relation to the graduations on the fixed dial, a hand adapted to move over the face of the movable dial, hydrostatic means connected with the movable dial and acting in direct response to the set radius of the boom to rotate the dial with reference to the iixed dial and thus indicate the radius at which the boom is set, separate hydrostatic means connected with said load responsive means and said indicating hand, the movable dial and indicatin T hand moving in unison as the angle of the boom changes, said separate hydrostatic means being responsive to the load imposed upon the free end of the boom and said load responsive means for moving the indicating hand over the movable dial when the angle of the boom has been fixed and thereby indicating the magnitude o the load with relation to the movable dial.

2. In combination with a boom crane, radius and load indicating means, comprising a xed circular dial having graduations therearound indicating boom radius and maximum safe load at a given boom radius, a movable circular dial carrying a pointer adapted to register with the graduations ci the xed dial as it moves, a hand mounted upon a pivot concentricaiiy of said dials and passing over the faces thereof, duid responsive weight indicating means connected with means for operating said hand to indicate the amounL of lifting force being applied at the free end of the boom and for moving the indicating hand as the boom angle changes, and hydrostati: means associated with the boom and the movable dial, whereby the movable dial will rotate to dispose its pointer at a calibration on the xed dial to indicate the radius of the boom and the maximum safe load which may be lifted by the boom at a particular radius.

3. An indicator of the character described adapted to operate in conjunction with a boom, comprising ,a case, a weight indicating Bourdon tube within the case, a radius indicating Bourdon tube within the case, a center pin, a sleeve rotatable with relation thereto, operating means between the rst named Bourdon tube and the pin for rotating the same under nexure of the tube. operating means connected with the second named tube and rotating the sleeve, a. xed annular dial having graduations thereon indicating radii of the boom and maximum safe loads for the boom at given radii, a rotatable dial disc mounted upon the sleeve and having a pointer to register with graduations on the fixed dial, said dial disc also carrying graduations indicating load weights, an indicating hand carried upon the pin and swinging over the faces of the dials and their calibrations, fluid pressure responsive means connected with means adjacent the free end of the boom and also connected with the rst mentioned Bourdon tube, whereby the weight imposed upon the free end of the boom will act to move ythe indicating hand appropriately, and hydrostatic means mounted at the free end of the boom and associated with the second named Bourdon tube to rotate the dial disc with relation to the iixed dial.

4. An indicator of the character described adapted to operate in conjunction with a boom, comprising a case, a weight indicating Bourdon tube within the case, a radius indicating Bourdon tube within the case, a center pin, a sleeve rotatable with relation thereto, operating means between the rst named Bourdon tube and the pin for rotating the same under fiexure of the tube, operating means connected with the second named tube and rotating the sleeve, a xed annular dial having graduations thereon indicating radii oi the boom and maximum safe loads for the boom at given radii, a rotatable dial disc mounted upon the sleeve and having a pointer to register with graduations on the fixed dial, said dial disc also carrying graduations indicating load weights, an indicating hand carried upon the pin and swinging over the faces of the dials and their calibrations, iiuid pressure responsive means including a closed receptacle having a yieldable wall, said receptacle containing an incompressible iuid, the wall being acted against by the load suspended at the end oi the boom, a tubular conduit connecting said receptacle with the first named Bourdon tube, a tubular conduit connected with the second named Bourdon tube, and a liquid reservoir carried at the free end of the boom and connected with said last named conduit, whereby i ation in elevation of the free end of the boom i ll cause proportionate variation in the hydrostatic head of the liquid in the reservoir and its conduit.

5. In combination with a crane including a boom having a hoisting block at the free end thereof and means by which the radius of the boom may be set adiustably, an indicating structure including a iixed dial having thereon graduations indicating boom radii and the maximum safe load for any given radius, a movable dial carrying graduations indicating the load imposed upon the boom and having a pointer moving with relation to the graduations on the nxed dial, a hand adapted to move over the face of the movable dial, means connected with the movable dial and acting in direct response to the set radius of the boom to rotate the dial with reference to the nxed dial and thus indicate the radius at which the boom is set and the maximum safe load to be lifted by the boom at said radius, means causing said hand to move in unison with the movable dial as said boom angle changes and to respond to the load imposed upon the free end of the boom for moving the indicating hand over the movable dial and thereby indicating the magnitude of the load.

6. In combination with a boom-type crane carrying a, hoisting block at its free end and having rneans by which the radius of the boom may be adjusted and the hoisting block raised, an indicating structure including a liquid filled conduit extending substantially from the base oi the hoorn to its outer free end and whereby as the radius of the boorn is shortened the hydrostatic head of liquid in the conduit will be increased, a duid responsive weight indicating structure connected with the hoisting block to indicate the amount of Weight imposed thereon, a conduit leading from said fluid responsive Weight indicating structure 4to a point near the free end of the boom and then leading downwardly to the base of the boom, said conduit and duid responsive means being lled With liquid whereby when the angle of the boom is shortened the hydrostatic head of liquid in this conduit will increase, an indicator disposed adjacent the base of the boom and within which a fluid responsive means is connected with the rst named conduit and a separate fluid responsive means Connected with the second named conduit, a iixed indicator ring carrying graduations desige hating diilerent lengths of boom radius and corresponding diiierenit safe loads, an indicator chart carrying an index point to move with reference to the graduations on the xed indicator ring and carrying graduations indicating different weights, said chart ybeing moved by the fluid responsive means connected with the first named liquid conduit, an indicating hand adapted to move over the face of said indicator chart as actuated by the second named fluid responsive means, a connection between the indicator chart and its iiuid responsive means, and a yieldable connection between the hand and its fiuid responsive means whereby a change in boom radius and a resultant change in the hydrostatic head of the liquids in the two conduits will cause the said indicator chart and indicating hand to move in unison and when weight is imposed upon the hoisting block to cause the indicating hand to move with relation to the said indicator Chart.

WALTER R. MARTIN.`

LOWELL LINDER.

HAROLD J. BLYTHE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,266,587 Hanser et al May 21, 1918 2,022,844 Christian Dec. 3, 1935 2,030,529 Nash Feb. ll, 1936 623,779 Grafton Apr. 25, 1899 1,795,465 Nash Mar. 1i), 1931 2,015,957 Neal et al Oct. 1, 1935 FOREIGN PATENTS Number Country Date 626,206 German Feb. 21, 1936 375,711 British June 30, 1932 

